Thermographic method for producing thermostable prints



9 E. M. BRINCKMAN 3,476,578

THERMOGRAPHIC METHOD FOR PRODUCING THERNOSTABLE FRINIS Filed June 22.1966 FIG; 2

INVENTOR ERIC MAR/A BRINCKMAIN WATSON, COLE, GR/NDLE & WA TSON ATTORNEYSUnited States Patent THERMOGRAPHIC METHOD FOR PRODIKIING THERMOSTABLEPRINTS Eric Maria Brinckman, Mortsel-Antwerp, Belgium, as-

signor to Gevaert-Agfa N.V., Mortsel, Belgium, a Belgian company FiledJune 22, 1966, Ser. No. 559,487 Claims priority, application GreatBritain, June 22, 1965, 26,468/65 Int. Cl. B41m /18; B44d 1/22; C08d13/24 US. Cl. 117-36.2 Claims ABSTRACT OF THE DISCLOSURE A thermographicreproduction method in which a heatlabile reactant of a two-reactantcolor-forming system carried in a heat-sensitive layer of aheat-sensitive recording material is rendered non-reactive by exposureto a heat image of the information to be reproduced and unaifectedreactant remaining in the unexposed areas of the layer are transferredto a copy material brought in contact therewith for reaction with thesecond reactant of the color-forming system provided on the copymaterial, producing on the copy material a colored image correspondingto the unexposed areas of the recording material. The heat-sensitivematerial preferably includes heat-absorptive material uniformlydistributed in heatconductive relation to the heat-sensitive layer, mostpreferably within the same layer, and the heat-absorptive materialpreferably converts electromagnetic radiation, especially infra-redradiation, to heat.

A recording material useful in the method is also disclosed whichincludes a heat-sensitive layer uniformly containing a heat-labilereactant of a color-forming system as well as a finely divided materialadapted to absorb infra-red radiation and convert the same to heat.

The present invention relates to a method of recording and reproducinginformation by means of heat. More particularly the present inventionrelates to a thermographic method for producing thermostable prints.

It is known to reproduce graphic originals by means of a heat-sensitivematerial containing chemical reagents, which on heating form a colouredproduct. However, the prints produced with such materials have thedrawback of not being thermostable.

In the process according to the present invention for recordinginformation a recording element is used containing a reactive compoundor composition which is destroyed, blocked or reduced in reactivity orremoved from the said element by the action of the image-wise orrecord-wise applied or induced heat. On the non-heated areas the saidcompound or composition remains at disposal for reacting with a compoundapplied thereto or can be transferred to a receiving element eg bydiffusion, tearing out, or vaporization so as to produce in thereceiving material a change in physical or chemical character, e.g. achange in light absorption, a change in colour or colour density. Achange in colour can be produced by a colour coupling reaction, a changein colour density by a bleaching out reaction.

The way wherein the heat is applied or induced imagewise or record-wisesupplied is of no importance. For various embodiments of image-wiseheating, which embodiments may also be applied in the present invention,there We refer to Belgian patent specification 656,713 which should beread in conjunction herewith. According to the embodiments particularlydescribed therein an infra-red radiation source is used for supplyingthe necessary heat energy. However, the recording of informationsupplied in the form of visible light is not ex- 3,476,578 Patented Nov.4, 1969 eluded since this light can be e.g. in the recording elementitself converted into heat.

The heat to be supplied during the recording step can be supplied byconduction of thermal motion, e.g. from infra-red absorbingimage-markings on an original to the heat-sensitive element, but ispreferably produced in the heat-sensitive element itself by theconversion of electromagnetic radiation into heat in substances that aredistributed in the heat-sensitive material and that are inheat-conductive contact with the compound or composition which has to bedestroyed, blocked in reactivity or removed from the heat-sensitiveelement by heating.

For recording techniques wherein use is made of such substances we moreparticularly refer to Belgian patent specification 657,502.

In order to obtain positive, legible prints a direct or reflectographicexposure technique can be used. However, a reflectographic exposuretechnique is preferably applied and using a recording materialcontaining in the recording element (e.g. layer) or in an element orcoating in heat-conductive relationship therewith, a substance orsubstances that absorb the copying light, and convert it into heat. Thetransparency of the recording material used for reiiectographic exposureis preferably such that at least 20% and at most of the copying light istransmitted. Refiectographic exposure is possible when carrying out thepresent invention, not only when the information to be recorded issupplied as a visible light pattern but also when it is supplied as apattern of infrared radiation if an element is used (whether formingpart of the recording material or not) which transmits a certain amountof infra-red radiation but is selectively or dilferentially heated inview of the radiation reflected from the original (see Belgian patentspecification 664,- 329). Whatever technique is selected it is to beunderstood that substances that absorb copying light (or infraredradiation) and convert it into heat may if desired be present in and/oron a layer other than the thermosensitive layer of the thermo-sensitivematerial, provided there is sufficient thermal contact to conduct heatgenerated therein to the thermo-sensitive substances. Such other layermay be another layer of the thermo-sensitive material or a layer (e.g. aself-supporting layer, or a supported layer or coating) forming orforming part of a material separate from the thermo-sensitive material,in other words a heat pattern can be firstly produced, in a separateelement and conducted therefrom to the heatsensitive material. For thetwo last mentioned embodiments particularly in view of the use thereinof a mainly infra-red emitting radiation source and copying apparatusreference is made to Belgian patent specification 664,329 which shouldto be read in conjunction herewith.

In its preferred form the recording process according to the presentinvention comprises the following features:

(a) Provision of a recording material or element containing a reactivecompound e.g. a coupler, which can be destroyed, blocked in reactivityor removed from the said element by the action of thermal motion that isimage-wise produced by image-wise reflected electromagnetic radiation ina substance or substances which is or are homogeneously distributed inthe thermo-sensitive element and absorbs said radiation and convert itinto heat, and

(b) Contact of the exposed recording element with a receiving materialor element containing a reactant for the compound or composition stillavailable, in order that transfer of said compound or composition bydiifusion in dissolved, evaporated or melted state to said receivingelement may take place possibly together with softened binder (if suchis present) which becomes torn out when the elements are subsequentlyseparated.

When applying a reflex exposure method the intensity of the exposure andthe sensitivity of the recording element containing said radiationabsorbing substances, which convert the applied radiation into heat, arechosen in such a Way that on the absorption of the light or other raysdirected to the original and striking undiiferentially thelight-sensitive layer, the heating resulting therefrom, causespractically no or only a slight inactivation or loss of the reactivecompound or composition. The additional image-wise heat resulting fromthe image-Wise reflected radiation produces in the recording materialthe practically useful image-wise elimination of the said compound orcomposition.

It is to be understood that when applying a reflectographic exposuretechnique the original to be reproduced must be an original containingimage areas or an imagebackground that reflect(s) copying radiation,e.g., light or a transparency which has copying light absorbing imageareas and which during the exposure is held with its back side incontact with or near proximity to a copying light reflecting material.

Having stated in general the concepts of this invention a detaileddescription will now be made of the composition and structure of variousheat-sensitive materials, types of radiation sources, and exposure,development and transfer techniques which can be used in the presentinvention.

For preparing a heat-sensitive material suitable for use according tothe present invention a colour reactant or colour bleaching compound orcomposition, which can be destroyed, blocked in reactivity or removedfrom the said element by heating, is applied with or without a binder toa suitable support. The support may be permeable so that said compoundor composition can be incorporated therein by impregnation. In the casea binder is used said binder can be chosen so that, in softened state,it can be transferred to a receiving material.

Suitable binders are ex. gelatin, carboxymethyl cellulose, tragacanthgum, alginic acid and the salts or esters thereof, poly(vinyl alcohol),poly(acryl amide), poly- 4 (vinyl pyrrolidone),ethylhydroxyethyl-cellulose, ethylcellulose, poly(vinyl butyral),cellulose triacetate, cellulose acetobutyrate,ethylcellulose-p-sulphonic acid benzoate, sucrose benzoate, poly(methylmethacrylate), polystyrene, polyethylene, polypropylene, poly(ethyleneterephthalate), copoly(vinyl chloride/alkyl acrylate),copoly(nitrostyrene/maleic acid/monoethyl maleate),copoly(styrene/monoethyl maleate), copoly(vinyl methyl ether/maleicanhydride), copoly(maleic acid/nitrostyrene), copoly(vinylchloride/methyl acrylate/ ethyl acrylate), partially nitratedcopoly(methyl acrylate/styrene), natural resins and waxes, e.g.,carnauba wax, beeswax and colophony.

Obviously a combination of two or more of the enumerated binders is alsosuitable, e.g., a mixture of gelatin and carboxymethylcellulose, gelatinand polyethylene in emulsified state, ethylcellulose and carnauba wax.

The binder and the thermo-sensitive compound or composition arepreferably dissolved in a common solvent. Binders insoluble in water maybe dissolved in an appropriate organic solvent, but they may be used asan aqueous emulsion (latex) as well. Solvents, which can be utilised inpreparing the heat-sensitive layer, are i.a. water, methanol, ethanol,ethylene glycol monomethyl) ether, methylene chloride, acetone,cyclohexanone, diethylene glycol, amyl acetate, dioxan, diethyleneglycol monoethyl ether, trichloroethylene, toluene, or a mixture of atleast two of the foregoing solvents.

The flexibility of the heat-sensitive layer can be secured by the use ofplasticizers such as glycerol, sorbitol, polyglycols, polyethyleneglycols, stearic acid and the esters thereof, esters of adipic acid andsebacic acid, polyethylene sebacate, polyethylene adipate,dimethylglycol phthalate, alkylaryl sulphonates, chlorinated diphenylcompounds, castor oil, pine oil, triphenyl phosphate, tricresylphosphate, and dibutyl phthalate.

In the following table appropriate combinations of colour reactants thatare suitable for use in the recording material (column A) and colourreactants that are suitable for use in a receiving material (column B)are grouped.

(1) Compounds splitting off sulphur such as dithiooxamide, thioacetamideand p-phenylenedithiourea.

(2) Acids such as oxalic acid, and malonic acid.

(3) Oxidising agents such as benzoyl peroxide,

and tetrachloroquinone.

(4) Couplers for diazotype such as 2,3-dihydroxy-iiaphthalene,phloroglucinol and resorcino (5) i-phenyl-B-pyrazolidinone andderivatives such as l-phenyl-4-methyl-3-pyrazolidinone, and1-(p-tolyl)-5-phenyl-3-pyrazolidinone.

(6) 8-hydroxy-l,2,3,4-tetrahydroquinoline and derivatives.

(7) Phenols and naphthols e.g. pyrocatechol, tert.-butyl-pyrocatech0l,pyrogallol, tort.- butyl-pyrogallol, 4-amino-1-naphthol,methoxy-I-naphthol, resorcinol, 2,3-dihydroxynaphthalene and1,4-dlhydroxynaphthaone.

(8) Compounds containing an active methylene group such asN,N-dimethylbenzamide and N -methylacetamide.

Inorganic and organic salts or soaps of iron, copper, silver, mercury,lead, nickel, cobalt and cadmium such as copper stearate, silvernitrate, silver stearate, silver behenate, silver palmitate, mercurystearate, lead acetate, lead stearate, lead myristate, nickel acetate,nickel stearate, cobalt stearate, cadmium stearate and lead benzylmercaptide.

Compounds that are sensitive to changes in the pH-value, e.g.leucomalachite green, leucomethyl green, leucofuchsine andleucolissamine green.

All compounds changing colour on oxidation e.g. p-chloroaniline,methyl-p-amino, phenol sulphate, N,N-d1methyl-p-phenylenediamine,antipyrine, pyrogallolpyrocatechol and 4methoxy-l-naphthol.

Aromatic diazo compounds e.g. the 4-(N,N-diethylamino)-benzene diazoniumdouble salt with zinc chloride, p-nitrobenzene diazonium fluoroborate,and pdiethylaminobenzene-diazonium tetrafiuoroborate.

Silver salts such as silver nitrate and silver behenate, gold salts suchas gold chloride and gold stearate, triazolium compounds such as2,3-diphenylnaphtho-[1,2]- triazolium chloride and2-pheriyl-3-(o-carboxy-phenyl)-naphtho-[1,2]-triazolium chloride,tetrazolium compounds such as 2,5-diphenyl-3-(o-carboxyphenyD- 2,l, 3,4tetrazo lium chloride and2,5-diphenyl-3-(p-rnethoxy-phenyl)-2,1,3,4-tetra- Z0lll. 1m chloride,leucophthalocyanines such as Phthalogene Blue IB (Farbenfabrikcn BayerAG, Leverkusen. W. Germany).

Inorganieand organic salts or soaps of iron, copper, silver, gold,cobalt and cadmium such as iron (III) chloride, iron (III) stearate,iron (II) chloride, iron (II) sulphate, 11011 (II) stearate, copper (II)chloride, copper (II) stearate, silver nitrate, silver behenate andcobalt (II) chloride. 7

Oxidising agents such as potassium dichromate and ammonium molybdate5-bi omo-2-amino-thiazoles e.g. 2-ethylamin0-4-phenyl-5-bromothiazoleand 2- diphenylaminoi-phenyl-fi-bromothiazole.

(9) Amines such as p-phenylenediamine, Aromatic aldehydes and ketoneseg; tetrachloroquinone, 1,4-naphthoquinone,

m-phenylenediamiue and d t anolainine.

z-chloronaphthoquinoiie, s-chlorovanillin -dimeth lamino-benzal eh do2,4-dinitro-benzaldehyde. p y d y and (10) Nitroso derivatives e.g.N-nitrosodiphenylamine, p-nitrosodimethylaniline andl-nitroso-2-naphthol.

(11)1riazene compounds such as 1,3di-

phenyl triazenez (12) Aromatic amines and aromatic aminohydroxycompounds eg l-amino-Z-naphthol, S-hydroxy-quinolme, pphenylenediamine,and m-phenylenediamine.

Aromatic hydroxy compounds e.g. pyrogallol, galllc acid,methylaminophenosulphate, and 4-methoxy-1-naphthol. -Metal salts e.g.iron (II sulphate and cobalt acetate. Amines, e.g. 2,5-diamino-tolueneand benzylaniline.

Coupling agents for diazotype printing e.g. 3-hydroxy-2-naphthanilideand 3- hydroxy-N-2-naphthyl-2-naphthamide.

Sulphur-containing compounds e.g. sodium sulphide, sodium trithionate,thioacetamide and thiourea.

Silver salts ag. silver nitrate, silver behenate, silver stearate, goldsalts e.g. gold (III) chloride and gold stearate.

Mercury salts e.g. mercury behenate.

(13) Nitro compounds e.g. 2-nitro-4 chloroaniline,1-chloro-2-nitro-4-diethyl sulphamoyl-benzene and dinitroresorcinol.

(14) Compounds that, on heating, set free alkali e.g. those describedinBelgian patent specification 612,963 and alkaline compounds eg.diethanolamine, tetramethylguanidine, p-phenylenediamine, andtriethylamine.

Metal salts eg. iron(III) chloride, iron(II) sulphate and cobaltacetate.

Oxidisable compounds such as 4-amlno-diphenylamine-2-sulphonic acid.

Compounds that change in colour when the pH changes, e.g. the leucoforrnof pnitrophenol, phanol-phthaleine, bromothymol blue chlorophenol red,bromo cresol purple, oxonol dyes and1,2,3,4-tetrahydro-4-[2-(3-methyl-2-henzothiazolinylidene)ethy1idene1-xanthylium-tetrachloroferrate(III).

Mixtures of a diazonium salt and a coupler e.g. the combination ofp-diethylamino-benzene diazonium tetrafluoroborate and phloroglucinol.

As radiation absorbing substances which can be in heat-conductiverelationship with the thermo-sensitive reactive compounds orcomposition, present in the recording element, are used e.g. infra-redand/or visible light absorbing pigments e. g. dispersable dyes. Aspigments are more particularly mentioned: carbon black, graphite, oxidesor sulphides of heavy metals having an atomic weight between 45 and 210,such as manganese, nickel and lead sulphide, or these heavy metalsthemselves in finely divided state such as silver, bismuth, lead, iron,cobalt and nickel. s

According to a special embodiment the thermosensi tive recording layer,during the exposure with visible light, is in uniform heat-conductiverelationship with coloured substances that absorb light of a determinedpart ofthe visible spectrum and convert it into heat; A thermosensitiverecording layer optically sensitised in this way can be used forrecording coloured light patterns.

-It is to be understood that mixtures of said coloured substances can beused too, so that light of the whole visible spectrum is absorbed.Further the said substances need not absorb in the range of the visiblespectrum alone; they may, absorb in the infra-red region although for.the recording'of red coloured image-markings ,the latter absorption ispreferably as. low as possible.

The coloured substances or mixture of said substances when-usedforoptical sensitization of the thermo-sensitive layer absorb preferablylight corresponding to at least one of the primary colours (red, green,blue or subtractive colours (cyan, magenta, yellow).

Substances that absorb visible lightof a part of the visible spectrumand wherein absorbed lightenergy is converted into heat are e.g. dyesbelonging to the classes of the azo dyes, the triarylmethane dyes, thexanthene dyes, the acridine dyes, the methine dyes, the azine dyes, thephthalocyanine dyes, the allied dyes.

In order toobtain a locally sufiiciently high heating efiect for theimage dilferentiation according ,to the present invention these dyes arepreferably used in finely; dispersed state. The grain size of the dyesis preferably lower than 0.1

Therecording material normally has an optical density of between :05 and1.50; in the case of reflectographic exposure it preferably has anoptical density for the light to be absorbed of between 0.20 and 0.80.

The reaction compounds in the heat-sensitive layer are preferably usedin an amount of 10'- to mol per sq.m.

anthraquinone dyes and The support (if any) for the heat-sensitiveelement is selected dependent upon the exposure technique applied, forexample, according to whether contact printing, in which the radiationis transmitted through the original to the heat-sensitive layer orreflex printing, in which the radiation is transmitted through theheat-sensitive layer to the original, is used. In the latter case thesupport should absorb as little copying light as possible. If theheat-sensitive element is a self-supporting layer, it is of course notnecessary for the recording: material to comprise a support from suchlayer.

In the direct contact printing method there are several variationspossible. For instance, the original, which is a transparency, is placedin contact with the heat-sensitive layer taking care that there iscreated no heat-conductive relationship of the image-markings with theheat-sensitive layer or such heat-conductive relationship is onlycreated to a minor extent (e.g. by applying no pressure). Theheat-sensitive layer contains a substance absorbing the copying lightand converting it into heat. According to another embodiment thetransparent document possessing light-absorbing characters, which areheated by the absorbed light, is placed with itscharacters in thermalcontact with the heat-sensitive layer, which, in that case, issufliciently transparent for the copying light.

In the normal reflex printing method, the original e.g. a line copy isplaced with the image bearing surface in thermal contact with theheat-sensitive layer and exposure takes place through the latter.

According to a special reflex printing method, which is moreparticularly described in the examples and illustrated by theaccompanying drawing and is also described in Belgian patentspecification 664,329, the heat-sensitive layer during reflectographicexposure does not stand in real thermal contact with the original, whichis chosen in such a way that it image-wise reflects the copying light orcontains a back-ground reflecting that light. In this case theheat-sensitive layer is in uniform thermal contact with a substance orsubstances that absorb(s) the copying light and convert(s) it into heatand that is or are present on and/ or in either an element of theheatsensitive material or a separate element that e.g. forms partof thecopying apparatus. For more details about such an apparatusv andseparate element: reference is made to Belgian patent specification664,329.

The heat-sensitive compound or composition which remained intact i.e.which is still present, after the imagewise exposure to heat, can bedeveloped on the recording material itself or transferred to a receivingmaterial containing a reactant for said compound or composition-Thetransfer can be carried out by means of a liquid or bynon-differentially supplying an amount of non-destructive heat in orderto vaporize or melt the thermosensitive image-forming compound orcomposition so that it can diffuse in that state to the receivingmaterial.

The non-destructive heat preferably effects in the heatsensitive elementan increase of temperature comprised between 50 and 250 C.

The effectiveness of the recording with electromagnetic radiation, whichyields the necessary energy for heating the recording element,substantially depends on the intensity of the radiant energy. Forexample, a recording layer that does not provide a sufficientdifferentiation in concentration of thermo-sensitive reactive compoundor composition with a particular source of electromagnetic radiationenergy may be fully effective if the energy level is substantiallyincreased.

Radiant energy of a brief duration and of high intensity is preferablyused.

Lamp structures and systems capable of providing high-intensityradiation in a very small lapse of time are well known per se.

Light sources with high radiation intensity and relatively shortexposure time are the' so-called flash lamps and more particularly thedischarge lamps containing an inert gas.

In the present invention good results are obtained with a xenon gasdischarge lamp, which can supply an energy of 300-3000 watt. sec. in atime interval of to 10* seconds. More details about a copying apparatuscontaining such a discharge lamp can be found in Belgian patentspecification 664,868. The intensity of emitted light is high in theinfra-red and particularly high in the regions of the visible spectrum.Temperatures up to 400 C. can be easily obtained in the radiationabsorbing substances by applying high intensity flash exposure.

It is possible to employ a number of flash tubes operatingsimultaneously or, in order to obtain a suitable imagedifferentiation,by flashing a single tube at suitable intervals. Reflectors and otheroptical components may be included to provide irradiation of maximumuniformity.

As illustrated by one of the examples hereinafter, which examplesillustrate the present invention without limiting it thereto, it is alsopossible to produce according to the invention, more particularlyaccording to the transfer technique set forth herein, multiple printsfrom one master only, which master has been formed by imagewise heatinga recording material as defined herein.

While emphasis has been placed on the recording of electromagneticradiation patterns it is to be understood that the invention includesthe recording of heat patterns heat of which is absorbed in thethermo-sensitive element or layer, and that it is possible to form aheatabsorbing image in the recording material itself eg if this materialis provided with a light-sensitive silver halide layer or a layer inwhich a silver-containing image can be formed by diffusion transfer.

The following examples illustrate the present invention Example 1 To acellulose triacetate support a heat-sensitive coating is applied, whichcoating is prepared as follows:

10 g. of powdered cellulose acetobutyrate (D.S. acetate 2.04, butyrate0.71) is mixed for 1 h. in a ball-mill with 0.5 g. of carbon black. Tothe mixed composition 300 ccs. of acetone are added and thereaftermilling is continued for another /2 h. To the suspension obtained asolution of 1 g. of thioacetamide in 99 ccs. of acetone is added. Thewhole composition is coated in such a way that after drying the coatingpossesses an optical density, measured in transmission, of 0.44.

As diagrammatically illustrated in the accompanying FIG. 1 theheat-sensitive material 39 is laid with its v heat-sensitive layer 41 ona graphic opaque original 42,

which possesses light-absorbing image markings and lightrefiectingback-ground. No intense pressure is applied so that there is no realthermal contact of the light-absorbing image markings with theheat-sensitive coating. The transparent cellulose triacetate support 40is directed towards a flash-exposure lamp 43 containing xenon gas. Theelectronic flash produces a light-intensity of 1600 watt. sec.

After flash-exposure the heat-sensitive material is brought into contactwith a receiving paper and led between a pair of rollers as illustratedin FIG. 2. The exposed heat-sensitive material 39, and the receivingmaterial 36 are pressed together between the rollers 37 and 38, theformer roller being heated to a temperature of 130 C.

After separating both elements a legible, pink positive print of theoriginal is obtained on the receiving material. The latter material isprepared as follows:

To a paper support weighing g. per sq. m. the following composition isapplied pro rata of 12.5 sq. in. per kg.:

Ethylcellulose having a substitution degree of 2.45 I

of ethyl groups g 30 Nickel stearate g 10 Amyl acetate ccs 970 Once thecoating is dry, the receiving paper is ready for use.

Example 2 Example 1 is repeated with the difference, however, that inthe heat-sensitive layer the amount of thioacetamide is replaced by asame amount of oxalic acid.

As receiving material a paper sheet is used, which has imbibed thefollowing solution and subsequently dried:

Sodium sulphite g 20 Fuchsine g 50 Water ccs 580 A legible, positive,pink print of the original is obtained on the receiving paper.

Example 3 Example 4 Example 1 is repeated with the difference, however,that in the heat-sensitive layer the amount of thioacetamide is replacedby a same amount of p-phenylenediamine.

As receiving material is used a paper support of 90 g. per sq. m. ontowhich the following suspension is coated pro rata of 12.5 sq. m. perkg.:

Ethylcellulose having a substitution degree of 2.45

of ethyl groups g 20 Silver stearate g 10 Acetone ccs 970 A legible,positive, brown print of the original is obtained on the receivingmaterial.

Example To a poly(ethylene terephthalate) support the followingheat-sensitive coating is applied:

Cellulose acetobutyrate (DS acetate:2.1, butyrate:

0.75) g Carbon black g 0.5 N-nitroso-diphenylamine g 1 Acetone ccs 489This heat-sensitive coating has an optical density, measured intransmission, of 0.61.

The receiving material is prepared by coating a paper of 90 g. per sq.m., pro rata of 13.5 sq. to. per kg., with the following composition:

Ethylcellulose having a substitution degree of 2.45

of ethyl groups g 20 Gallic acid g 10 Acetone ccs.. 970

When proceeding as described in Example 1, a legible, positive,brown-grey print of the original is obtained on the receiving material.

Example 6 Example 5 is repeated with the difference, however, that theamount of N-nitroso-diphenylamine is replaced by a same amount of tert.butyl-pyrogallol and that the amount of gallic acid in the receivingmaterial is replaced by a same amount of iron(II) stearate.

A legible, positive, purple-grey print of the original is obtained.

Example 7 Example 5 is repeated with the ditference, however, that theamount of N-nitroso-diphenylamine is replaced by a same amount ofphloroglucinol and that the amount of gallic acid in the receivingmaterial is replaced by a same amount of pdiethylaminobenzene diazoniumtetra fiuoroborate.

A legible, positive, brown-grey print of the original is obtained.

Example 8 Example 5 is repeated with the difierence, however, that theamount of N-nitroso-diphenylamine is replaced by ,a same amount of4-methoxy-l-naphthol and that the material described as such in Example4 is used as receiving material.

A legible, positive, green print of the original is obtained.

If the carbon black is excluded from the recording material, noimage-differentiation is obtained on the receiving material. Thereceiving material becomes uniformly green coloured. If the carbon blackin the recording material is replaced by 0.5 cc. of a 10% ethanolicsolution of erythrosine, a known optical sensitizing dye, noimagedifferentiation can be obtained also, even not by increasing theadded amount of sensitizing solution to 5 cos.

Example 10 Example 5 is repeated with the difierence, however, that theamount of N-nitroso-diphenylamine is replaced by a same amount ofp-phenylenedithiourea and that a paper as described in Example 4 is usedas receiving material. After having been dried, the recording materialpossesses an optical density, measured in transmission, of 0.29.

A legible, positive, brown print of the original is obtained.

Example 11 Example 5 is repeated with the ditference, however, that theamount of N-nitroso-diphenylamine is replaced by a same amount of1,3-diphenyl-triazene and that the amount of gallic acid in thereceiving paper is replaced by a same amount of3-hydroxy-N-2naphthyl-2-naphthamide.

A legible, positive, orange-red print of the original is obtained.

A glassine-type paper weighing 60 g. per sq. m. is coated with aheat-sensitive layer from the following composition:

Cellulose acetobutyrate (DS acetatezll, butyrate:

0.75 g 10 Carbon black g 0.5 Tetrachloroquinone g 1 Acetone cs..- 489Ethylcellulose having a substitution degree of 2.45

of ethyl groups g 20 4-metl1oxy-1-naphthol g 10 Acetone 970 A legible,positive, blue print of the original is obtained when proceeding asdescribed in Example 1.

Example 13 To a poly(ethy1ene terephthalate) support a heat-sensitivecoating is applied from the following composition:

Cellulose acetobutyrate (DS acetate:2. 04, butyrate:

0.71) g 10 Carbon black g 0.5 Dithiooxamide g 0.5 Acetone ccs 489 Afterhaving been dried the heat-sensitive material possesses an opticaldensity, measured in transmission, of 0.54.

As receiving material a paper of g. per sq. m. is used onto which thefollowing suspension is coated:

Ethyl-cellulose having a substitution degree of 2.45

of ethyl groups 2 20 Silver behenate v g 10 Amyl acetate ccs... 970

The suspension is coated in such a Way that an amount of silver behenatecorresponding to 0.15 of silver is present per sq. m.

A legible, positive, brown print of the original is obtained whenproceeding as described in Example 1.-

Example 14 Example 13 is repeated with the difference, however; that theamount of carbon black in the heat-sensitive ma: terial is replaced by asame amount of finely divided nickel sulphide.

A legible, positive, brown print of the original is obtained.

Example 15 Example 13 is repeated with the difference, however, that theamount of carbon black in the heat-sensitive material is replaced by asame amount of Indigo Blue (0.1. 73,000).

A legible, positive, brown print of the original is obtained on thereceiving material.

1 1 Example 16 Example 13 is repeated with the difference, however, thatthe amount of dithiooxamine in the heat-sensitive material is replacedby a same amount of tert.-butylpyrocatechol.

A legible, positive, brown print of the original is obtained on thereceiving material.

Example 17 Example 13 is repeated with the difference, however, that theamount of dithiooxamide in the heat-sensitive material is replaced by asame amount of 1-phenyl-3- pyrazolidinone. By repeating the transferstep five times, each time with another image receiving blank, fivesharp prints of the original can be obtained.

Example 18 A cellulose triacetate support, provided with a subbing layerfor a hydrophilic colloid layer, is coated with a heat-sensitive layerfrom the following composition:

Poly(vinyl alcohol) g 30 Dimethylolurea g 20 p-Toluenesulphonic acid gAqueous dispersion containing per 100 ccs. 0.5 g. of

black silver and 3.4 g. of gelatin ccs 120 5% ethanolic solution oftert.-butylpyrocatechol ccs 11% aqueous solution of saponin ccs 30 Waterto ccs 1000 Example 19 Example 1 is repeated with the difference,however, that the heat-sensitive layer is exposed by transmissionthrough a silver image transparency.

What I claim is:

1. In a method of reproducing information using a color-forming reactionsystem comprising two reactants adapted to react to produce a coloredreaction product, the improvement which comprises exposing aheat-sensitive recording material including a heat-sensitive layeruniformly containing a color-forming reactant which is affected by heatof sufiicient intensity and is selected from the group consisting ofcompounds which are destroyed by heat, compounds which are blocked inreactivity by heat, and compounds which are removed by heat, to a heatimage of the information to be reproduced of sufficient intensity toaffect said reactant in the heated areas; bringing the heat-sensitivelayer of said exposed heatsensitive material into effective contact witha copy material having the other of said color-forming reactantsuniformly distributed thereon; and transferring at a temperature belowthat at which said first reactant is affected at least a portion of saidfirst reactant from the unexposed and unheated areas of saidheat-sensitive material to said copy material, the transferred firstreactant reacting with the second reactant to produce on the copy sheeta colored image corresponding to the unexposed areas of saidheatsensitive material.

2. The process of claim 1 wherein said heat-sensitive material while theheat-sensitive layer thereof is in effective contact with copy materialis subjected to heat below the intensity at which said first reactant iseffected to facilitate transfer of said first reactant to said copymaterial.

3. The process of claim 1 wherein said heat-sensitive layer includes abinding agent adapted to soften upon heating a stratum of said layercontaining said first reactant is bodily transferred to said copymaterial to produce said color-forming reaction.

4. The process of claim 1 wherein said heat-sensitive material includesin heat-conductive relation to said heatsensitive layer heat-absorptivematerial uniformly distributed thereover.

5. The process of claim 1 wherein said heat-absorptive material and saidfirst reactant are contained in a common layer.

6. The process of claim 1 wherein said heat-sensitive layer includes inheat conductive relation to said heatsensitive layer a vmaterial adaptedto absorb and convert electromagnetic radiation into heat and saidheat-sensitive material is exposed to an image of said radiation.

7. The process of claim 6 wherein said radiation absorbing andconverting material and said first reactant are contained in a commonlayer.

8. The process of claim 6 wherein said heat-sensitive material isexposed to a high intensity radiation source emitting infra-red andvisible radiation within an interval of not more than about sec. ofsufficient intensity to heat the exposed areas of said heat-sensitivelayer to render the first reactant contained therein non-reactive.

9. The process according to claim 6 wherein the heatsensitive layercontains a reactive compound selected from the group consisting of1-phenyl-3-pyrazolidinone, 1,3- diphenyltriazene, tetrachloroquinone and4-methoxy-lnaphthol.

10. The process of claim 9 wherein said second reactant on said copysheet is a reducible silver salt.

References Cited UNITED STATES PATENTS 2,916,395 12/1959 Owen 11736.82,936,247 5/1960 Francis et al. 11736.1 2,992,121 7/1961 Francis et al11736.1 3,210,544 10/1965 Marx et al 25065.1 3,223,838 12/1965 Hoshinoet a1 250-651 3,238,047 3/1966 Murray et al 1l7--36.8 3,262,386 7/1966Gordon 11736.8

MURRAY KATZ, Primary Examiner U.S. Cl. X.R.

